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Friday, December 14, 2012

Hear, Hear! A Call for Music

I got my information from a TED Talk by Charles Limb and from an MIT Technology Review article by Michael Chorost.

Science and technology have made
amazing progress in terms of aiding the hearing impaired. In the 16-
and 1700s, the best science had to offer were hearing trumpets that
funneled sound to the ear from a larger opening at the opposite end
of the device. Later on, in the 1800s, attempts were made to make
hearing aids more subtle, though perhaps a bit ridiculous, like
ear-shaped devices with small funnels that one would wear like
earmuffs. Todays cochlear implants are a vast improvement over, say,
walking around with two sets of ears. Unlike hearing aids, which
amplify sounds, cochlear implants directly stimulate the auditory
nerve which sends sound signals to the brain, bypassing any damaged
portions of the ear. Their primary function is to help people hear
spoken language. This, of course, is great and tremendously useful,
but CIs still have many challenges to face. One of these challenges
is allowing its users to hear music.

Today's cochlear technology relies on
the semantic-specific nature of spoken language. What matters is that
a message is communicated correctly, not that the message sounds nice
when spoken. In more visual terms, the letter “t” can be written
many different ways depending on a person's handwriting or a font
used on the computer. The visual aspect of the “t” is
unimportant. All that is needed is the recognition that it is the
letter “t” and not any other symbol. This is the way spoken
language works, and so that is what cochlear technology uses to aid
in hearing and communication. Music, however, works almost
oppositely. What is music if not something that sounds nice?

This graph shows the difference between the sound levels and frequencies needed to hear spoken language and those needed to hear music. CIs only transmit what is needed to hear language.

One of the main problems with CIs
allowing people to hear music is a matter of pitch perception. Most
people with standard hearing can differentiate between pitches that
are 1.1 semitones, the smallest pitch interval in Western music,
apart. CI patients' pitch perception can be off as much as two
octaves. This is a considerable difference. Another problem arises
with the inability of most cochlear implant users to discern between
various instruments. With a device that focuses on the fundamentals
of communication rather than sound quality, things like warmth and
timbre are not transmitted.

Researchers at the University of
Washington and the University of Iowa are working on breaking down
the components of music to help CI users hear it. Their computerized
test called the Clinical Assessment of Music Perception (CAMP)
divides the very complicated unit known as music into three parts:
pitch, timbre, and melody. The perceptibility of each component can
be tested by CI patients, and these tests have shown the presence of
the ability to perceive pitch. The tests can also show progress over
time, perhaps with advances in technology. For example, if test
scores improve, there is a good possibility that music perception is
actually increasing amongst CI patients.

Beethoven managed to compose beautiful
music in spite of his profound deafness. If he accomplished so much
with a simple hearing trumpet, imagine what can be done with today's
ever-evolving technology. Both music and human beings are extremely
complex, but beautiful in their complexity, so to get them to work
together in (are you ready for it?) harmony will be an amazing
accomplishment. The universal ability to hear music may be a long way
off, or that technology might be available within the next few years.
Who knows? Either way, I'm excited. Music is just one of those things
that can't be explained. It has to be experienced firsthand, and
everyone should have to opportunity to feel it.